1. Field of the Invention
The present invention relates to an apparatus and a method for metering and transferring an extremely cold liquid from a supply vessel to a receiving vessel. The liquids intended for transfer by the apparatus and method of this invention exist as a gas at normal atmospheric temperature and pressure and will hereafter in this specification be identified as cryogenic liquids. The present invention is particularly adapted for, but not limited to, the efficient transfer of cryogenic liquid fuels, especially liquefied natural gas (LNG), or methane, from a storage tank to a vehicle fuel tank.
2. Description of Prior Art
Known apparatuses and methods for effecting the transfer of cryogenic liquids require a series of manual operations which require skilled operators, entail substantial time and expense and invite damage to equipment and loss of valuable cryogenic liquids. Also, due to the extremely cold temperatures of the liquids being handled, discomfort or injury to operating personnel are likely. In addition, because these liquids have a strong tendency to vaporize when exposed to normal atmospheric temperatures and pressures, it becomes difficult to meter the liquids and to realize flow rates that allow for expeditious liquid transfer.